1. Technical Field
The present invention relates to pumps and in particular to linear diaphragm air pumps.
2. Description of the Related Art
Air compressors and pumps are well known. Some are large reciprocating piston and cylinder pumps for high flow volume commercial or industrial applications and others are compact units for lesser flow home applications. One example of the latter is inflating a bladder membrane, such as an air mattress for an air bed. Pumps for inflating and deflating air mattresses need to provide rapid pressurization while being both compact and quiet.
U.S. Pat. No. 5,606,756 discloses an example of a pump for an air mattress application. This pump has a motor rotated shaft mounting two canted flanges at opposite ends with push and pull sets of diaphragm pistons causing air flow. The pump is contained in a single, compact housing which is partitioned into essentially five compartments, including a motor chamber, two valve chambers (one on each side of the motor chamber), an end chamber and a solenoid chamber. The motor chamber is open to ambient pressure and the valve chambers become pressurized by movement of the diaphragms. Valves control flow from the valve chambers to the solenoid chamber, with flow from one valve chamber passing first through the end chamber and then through an internal conduit passing through the motor and other valve chambers. Two solenoids control flow of pressurized air to lines connected to each bladder of the air bed.
U.S. Pat. No. 6,483,264 provides another example of an air pump for an air bed. Here, the pump has a motor operated impeller disposed in a sub-housing section of the pump unit. The impeller sends pressurized air through an internal passageway to another sub-housing containing two solenoids controlling air flow to the mattresses.
While both of these units are designed to be relatively compact and quiet as well as produce sufficient air flow volume and pressure for use in an air bed, they each have attributes that make them somewhat disadvantageous. The '756 device has a relatively complicated drive arrangement and requires an extra air chamber and transfer tube for one set of diaphragms, thus increasing its footprint as well as its component and assembly cost. The '264 device requires multiple individual housing sections that must be properly assembled and sealed to avoid leakage and allow the pump to operate efficiently, and the impeller and associated housing chamber necessitates a somewhat larger overall unit. Moreover, both devices have rotating motors that can wear and become noisy or decrease the operational life of the unit.
It would be beneficial, therefore, to provide an improved pump unit suitable for inflatable devices, such as air beds, having integral pump and valve assemblies in a housing of simplified construction.